The present invention relates to a linear conveying unit for transferring items and, in particular, to a saddle which moves linearly along a track.
Such a conveying unit may include a tubular bar having a longitudinal opening or channel along which the saddle is linearly movable, preferably by using a motor to drive a toothed belt or a screw for example in a manner known per se. The saddle is equipped with at least two groups of wheels placed at opposite ends of the saddle, the wheels of each group lying in a common plane oriented perpendicular to the longitudinal direction of the saddle. The wheels engage linear tracks formed by the bar.
Such linear conveying units are widely used to transport products, machine parts or the like from one place to another, in horizontal, vertical or inclined directions.
It is necessary to ensure that gaps do not exist between the wheels and tracks, e.g., by adjusting the wheels or tracks. Such adjustments have proven to be complicated and time-consuming. For example Folk U.S. Pat. No. 3,427,080 discloses the use of a wedge which is displaceable to adjust a track toward and away from the wheels located on one side of the saddle. Such a mechanism is cumbersome and complicated.
German DE-C-33 36 496 illustrates a saddle having front and rear groups of wheels oriented such that the wheel axes of each group lie in a common plane oriented perpendicular to the saddle axis. The planes of the front and rear groups are mutually parallel. To eliminate the gap between the wheels and the track, each wheel is provided with its own individual eccentric adjustment mechanism. However, this individual adjustment is time-consuming and requires that each adjustment device be accessible from the outside of the rail in order to enable the adjustment to be made.
In Beninger et al U.S. Pat. No. 2,997,346, individually adjustable wheels are mounted on the bar rather than on the saddle. However, such an arrangement can be prohibitively expensive if a large number of wheels are required. Also, if the wheels are not similarly adjusted operational difficulties can result, as noted above.
In many instances, prior art arrangements require that the saddle and/or bar be partially dismantled in order to effect an adjustment of the wheels. Since the conveying units may consist of many different parts, it may be necessary to dismantle a plurality of parts when adjusting a wheel or a notched belt. This is unacceptably time-consuming, especially since the wheel adjustments themselves are rather simple.